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Title: Computational and experimental study of the Volcano behavior of the oxygen reduction activity of PdM@PdPt/C (M = Pt, Ni, Co, Fe, and Cr) core-shell electrocatalysts
Authors: Trinh, Q.T.
Yang, J.
Lee, J.Y. 
Saeys, M. 
Keywords: Core-shell catalysts
Density functional theory
Oxygen reduction reaction
Sabatier principle
Volcano behavior
Issue Date: Jul-2012
Citation: Trinh, Q.T., Yang, J., Lee, J.Y., Saeys, M. (2012-07). Computational and experimental study of the Volcano behavior of the oxygen reduction activity of PdM@PdPt/C (M = Pt, Ni, Co, Fe, and Cr) core-shell electrocatalysts. Journal of Catalysis 291 : 26-35. ScholarBank@NUS Repository.
Abstract: The activity of oxygen reduction electrocatalysts is governed by the Sabatier principle and follows a Volcano curve as a function of the oxygen-binding energy. Density functional theory calculations show that the oxygen-binding energy decreases in steps of about 10 kJ/mol in a series of core-shell Pd 3M@Pd 3Pt (M = Ni, Co, Fe, Mn, and Cr) electrocatalysts, leading to a gradual, Volcano-like variation in the oxygen reduction activity. A series of carbon-supported PdM@PdPt (M = Ni, Co, Fe, and Cr) nanoparticles with similar particle sizes were prepared by an exchange reaction between PdM nanoparticles and an aqueous solution of PtCl42-. The variation in the surface electronic structure of the core-shell structures was evaluated by Pt 4f 7/2 X-ray photo-electron spectroscopy and by CO-stripping voltammetry and agrees with the first principle calculations. At 0.85 V, the PdM@PdPt/C core-shell electrocatalysts show a 6-fold variation in activity, following the Volcano trend predicted by the calculations. The Pt mass activity of the Volcano-optimal PdFe@PdPt/C catalyst is an order of magnitude higher than the activity of commercial 3.0-nm Pt/C catalysts. The core-shell catalysts also display a high methanol tolerance, which is important for use in direct methanol fuel cells. Calculated Pt-M segregation energies suggest that the Pd 3M@Pd 3Pt core-shell structures are stable, in particular in the presence of 1/4 ML CO. Adsorption of oxygen-containing species may induce surface segregation of the 3d transition metal, except for the Volcano-optimal ORR catalyst, Pd 3Fe@Pd 3Pt. © 2011 Elsevier Ltd. All rights reserved.
Source Title: Journal of Catalysis
ISSN: 00219517
DOI: 10.1016/j.jcat.2012.04.001
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